Polymerization process and catalyst system

ABSTRACT

UTILIZATION OF A CATALYST SYSTEM FORMED BY ADMIXING (A) A COMPOUND OF THE FORMULA RNA1X3-N; (B) A TITANIUM TRICHLORIDE-ALUMINUM TRICHLORIDE COMPLEX OOF THE APPROXIMATE FORMULA TIC13-1/3 ALC13; AND (C) A TETRAKIS (HALOALKYL) PHOSPHONIUM HALIDE OF THE FORMULA (XR&#39;&#39;)4P+)XIN THE POLYMERIZATION OF 1-OLEFINS RESULTS IN THE PRODUCTION OF POLYMERS HAVING IMPROVED PROPERTIES. IN THE ABOVE FORMULAS, R IS SELECTED FROM ALKYL, CYCLOALKYL AND ARYL GROUPS, AND COMBINATIONS THEREOF, HAVING FROM 1 TO 12 CARBON ATOMS, R&#39;&#39; IS AN ALKYLENE GROUP CONTAINING 1 TO 4 CARBON ATOMS, N IS 1, 2 OR MIXTURES THEREOF, AND X IS HALOGEN.

United States Patent ce 3,600,370 Patented Aug. 17, 197i 3,600,370 POLYMERIZATION PROCESS AND CATALYST SYSTEM Lawrence M. Fodor, Bartlesville, Okla, assignor to Phillips Petroleum Company No Drawing. Filed Oct. 10, 1968, Ser. No. 766,635 Int. Cl. C08f 1/56, 3/10 US. Cl. 26093.7 6 Claims ABSTRACT OF THE DISCLOSURE Utilization of a catalyst system formed by admixing (a) a compound of the formula R AlX (b) a titanium trichloride-aluminum trichloride complex of the approximate formula TiCl 1/3 AlCl and (c) a tetrakis (haloalkyl) phosphonium halide of the formula [(XR') P+]X in the polymerization of l-olefins results in the production of polymers having improved properties. In the above formulas, R is selected from alkyl, cycloalkyl and aryl groups, and combinations thereof, having from 1 to 12 carbon atoms, R is an alkylene group containing 1 to 4 carbon atoms, n is 1, 2 or mixtures thereof, and X is halogen.

BACKGROUND OF THE INVENTION Polymers of alpha-olefins, particularly of propylene, have long been known and numerous procedures have been disclosed for their production. These polymers are characterized by a greater or lesser degree of stereospecificity; they also vary in degree of crystallinity. Many of the useful properties of these polymers such as ultimate tensile, hardness, range of melting temperature, etc., appear to depend upon the crystallinity of the polymer. Flexural modulus, a property readily measurable by standard procedures, provides a reliable and consistent means for characterizing these polymers. The higher the crystallinity of a polymer the higher the flexural modulus values are found to be. For a commercially attractive product, flexural modulus values must be high, preferably above 190,000 p.s.i. Heretofore, it has been frequently necessary to extract amorphous fractions of the polymer in order to provide products having ilexural moduli in this range. It is therefore highly desirable to minimize the production of amorphous polymer as measured for example by the amount of polymer soluble in mixed xylenes. It is further desirable to obtain a polymer having a good balance of properties such as elongation, tensile strength and melt flow.

It is thus an object of this invention to provide an improved process for the production of olefin polymers.

Another object of this invention is to provide a polymerization process in which there is obtained a product having an increase in fiexural modulus and a decrease in the xylenes-soluble content.

A further object of this invention is to provide a novel catalyst system which, when employed in the polymerization of l-olefins, results in an increase in the flexural modulus and a decrease in the xylenes-solubles content of the resulting polymer.

Other aspects, objects and the several advantages of this invention will be apparent to those skilled in the art upon consideration of this disclosure.

According to this invention, I have discovered that polymers of l-olefins (alpha-olefins) can be obtained having increased flexural modulus values and a decreased xylenes-solubles content when the polymerization is conducted in the presence of a catalyst system formed by admixing (a) an organoaluminum compound or mixture of such compounds of the formula R AlX wherein R is alkyl, cycloalkyl, aryl or combinations thereof having 1 to 12 carbon atoms, X is a halogen and n is 1, 2 or mixtures thereof; (b) a titanium trichloride-aluminum trichloride complex such as that resulting from the reaction of titanium tetrachloride and aluminum and having the approximate formula TiCl l/ 3 AlCl and (c) a tetrakis (haloalkyl) phosphonium halide of the formula wherein R is an alkylene group containing 1 to 4 carbon atoms and X is halogen.

The enumeration of alkyl, cyclo-alkyl and aryl radicals herein in defining the formulas is intended to include the various mixed radicals such as alkaryl, aralkyl, alkylcycloalkyl, cycloalkylaryl, and the like.

The compounds and mixtures of compounds represented by the formula R AlX and utilized as component (a) of the catalyst system of the invention are well known in the art. Examples of such compounds are diethylaluminum chloride, ethylaluminum dichloride, ethylaluminum sesquichloride and the like.

The titanium chloride-aluminum chloride complex utilized as component (b) of the catalyst system according to this invention is also well known in the art. It can be formed, for example, by reacting titanium tetrachloride with metallic aluminum. The complex can be represented by the formula TiCl 1/3 AlCl Examples of the tetrakis (haloalkyl) phosphonium halide compounds of the formula [(XR') P+]X which are component (c) of the catalyst are tetrakis (chloromethyl) phosphonium chloride, tetrakis(bromomethyl) phosphonium iodide, tetrakis(l-chloroethyl) phosphonium bromide, tetrakis(2-bromoethyl) phosphonium iodide, tetral is( l-methyl-Z-chloroethyl phosphonium bromide, tetrakis(4-iodobutyl) phosphonium chloride, tetrakis(2-methyl-3-fluoropropyl) phosphonium chloride, tetrakis(1-ethyl-2-iodoethyl) phosphonium fluoride, and the like.

Broad and preferred ranges for the molar ratio of the catalyst components are:

The total catalyst concentration is usually in the range of 0.005 to 10 weight percent of the olefin being polymerized, but concentrations outside this range are operative.

The polymerization reaction is carried out either in a mass systemi.e., the olefin being polymerized acts as the reaction mediumor in an inert hydrocarbon diluent, such as a parafiin, cycloparafiin, or aromatic hydrocarbon or mixtures thereof having up to 20 carbon atoms per molecule. Examples of hydrocarbons that can be used are pentane, hexane, isooctane, eicosane, cyclohexane, methylcyclopentane, benzene, toluene, naphthalene, anthracene and the like. When an inert diluent is used, the volume ratio of diluent to olefin is in the range of 1:1 to 10:1, preferably 3:1 to 7:1.

The polymerization is conducted at temperatures in the range of to 250 F., preferably to 200 F. The pressure can be sufficient to maintain the reaction mixture substantially in the liquid phase, or-particularly in a mass systemcan be such that the olefin is in the vapor phase. The reaction time is in the range of 10 minutes to 75 hours, more frequently 30 minutes to 25 hours.

Although the invention is illustrated by the polymerization of propylene, any aliphatic l-olefin having up to 8 carbon atoms per molecule can be used. Preferably those having 3 to 7 carbon atoms are used, such as propylene, 1 butene, l-hexene, 4-methyl-1-pentene, l-

Data illustrating the process of the invention were obtained by polymerizing propylene in a 1-liter, stirred reactor in 2.5-hour runs at 130 F. and about 300 p.s.i.g. with 250 grams of propylene and 0.021 mol of hydrogen (equivalent to 0.35 mol percent hydrogen based on the propylene) present in the reaction system. As catalyst, there was employed a mixture of diethylaluminum chloride, TiCl -l/ 3 AlCl and tetrakis(chloromethyl) phosphonium chloride.

The following results were obtained:

'2. A catalyst system according to claim '1 formed by admixing (a) diethylaluminum chloride; (b) a'titanium trichloride-aluminum trichloride complex of the formula TiCl -1/3AlCl and (c) tetrakis (chloromethyl) phosphonium chloride.

3. A process which comprises polymerizing an aliphatic l-olefin having from 3 to 8 carbon atomsper molecule in the presence of a catalyst which formson mixing (a) a compound of the formula R AlX Wherein R is alkyl, eycloalkyl, aryl or combinations thereof having l'to 12 carbon atoms, X is ,a halogen, and n is.

1, 1.5, or 2; (b) a titanium trichloride-aluminum'tri-' chloride complex of the formula TiCl -l/3AlCl andv (c) a tetrakis (haloalkyl) phosphonium halide of-the formula [(X|R) P+]X wherein R is an alkylene groupcontaining 1 to 4 carbon atoms and. X is halogen and wherein the molar ratio of (a) to (b) is in the range of" 0.5:1 to 10:1 and the molar ratio of (c) range of 0.01:1 to 3:1.

4. A process according to claim 3 wherein said cata-;

lyst is formed by admixing (a) diethylaluminum chlo-' Wt. percent C a1 t 111011 tio catal st Percent Flexural at ys a based bn xylene Melt modulus, Elongation, Tensile, Ti olefin solubles flow p.s.i. 10- 0 percent d p.s.1. d

( Determined by placing 0.95 g. of polymer in a centrifuge tube, adding 95 ml. mixed xylenes, heating for 15 minutes at 28 liquid, weighing the residue, and multiplying by 400.

b ASTM D 1238-62T, condition L. n ASTM D 790-63. d ASTM D 638-61T; crosshead speed 2/min. e Break.

The above data show that utilization of the catalyst system of the invention results in an increase in flexural modulus of the polymer obtained therewith when compared with polymer made in the absence of the phosphorus compound. In addition, the data also demonstrate that improvements were obtained in elongation, tensile strength and, in most instances, in xylene soluble content of the polymer.

Reasonable variations and modifications of this invention can be made, or followed, in view of the forelgoing disclosure, without departing from the spirit or scope thereof.

I claim:

1. A catalyst system formed on admixing (a) a compound of the formula R AlX wherein R is alkyl, cycloalkyl, aryl or combinations thereof having 1 to 12 carbon atoms, X is a halogen, and n is l, 1.5, or 2; (b) a titanium trichloride-aluminum trichloride complex of the formula TiCl -l/3AlCl and (c) a tetrakis (haloalkyl) phosphonium halide of the formula [(XR) P+]X wherein R' is an alkylene group containing 1 to 4 carbon atoms and X is halogen and wherein the molar ratio of (a) to (b) is in the range of 0.5;1 to 10:1 and the 5 F., cooling, centrifuging, evaporating the solvent from a 25-ml. aliquot of the supernatant ride; (b) a titanium trichloride-aluminum' trichloride complex of the formula TiCl -1/3AlCl and (c) tetrakis (chloromethyl) phosphonium chloride.

5. A process according to claim 4 wherein the polymerization is carried out at a temperature in the range of 80 to 250 F. and a pressure sufficient to maintain'the' reaction mixture in the liquid phase.

6. A process according to claim 5 wherein said l-ole- JOSEPH L. SCHOFER, Primary Examiner E. 1. SMITH, Assistant Examiner US. Cl. X.R.

to (b) is in the; 

